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Animal Production > Pregnancy > Flashcards

Pregnancy Flashcards

1
Q

Marked placental growth

A

Occurs prior to significant fetal growth
-increased placental blood vessel growth and vasodilation supports fetal growth
-placental transport of nutrients, gases, growth promoting factors are needed for fetal growth/development
-assisted by areolar growth

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2
Q

Progesterone during gestation

A
  1. Early pregnancy: progesterone stimulates endometrial growth and gland development and secretions
  2. Progesterone block: inhibits uterine contractions
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3
Q

Luteo-placental shift

A

When placental progesterone takes over from CL to maintain pregnancy

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4
Q

Timing of luteo-placental shift

A

Varies among species
-pigs, goats, dogs, alpacas, llamas, rabbits do not have the ability to produce enough placental P4 to avoid abortion when ovaries removed
-cows- can remove ovaries after 8mths
-Does not occur in cats (but placenta still makes enough P4). Due to CL being present entire time
-Horses, humans and sheep undergo this shift

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5
Q

Estrogens/Estradiol during gestation

A

Produced by placenta
-Early pregnancy: stimulates endometrial growth
-Parturition period: peak of estradiol
-Labour: Increased estradiol

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6
Q

Placental Lactogen production

A

-Peptide hormone also called chorionic somatomammotropin

-produced by trophoblasts (but in ruminants by BNGC and TNCs)

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7
Q

Which animals have placental lactogen?

A

rodents, sheep, cow, goat, humans

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8
Q

Placental lactogen fetal vs. maternal

A

**like growth hormone

Secreted into maternal and fetal circulations

Fetus: varies; sheep increases early then remains constant.
-Bovine: will decline in levels throughout pregnancy

Maternal: steady increase in levels up to parturition

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9
Q

Placental lactogen function

A

-Stimulates mammary gland growth/development in the dam but also plays a smaller role in fetal growth

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10
Q

Placental lactogen effect on fetal growth

A
  1. Due in part to induction of growth promoting factors in the fetus (insulin growth factors)
  2. Anti-insulin effect on dam- freeing up maternal glucose stores for fetus
  3. Stimulates amino acid uptake
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11
Q

Timing of PAG productions during gestation

A

-Maternal circulation as early as day 24 of gestation and peak before parturition

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12
Q

Functions of PAGs

A

*many different forms of PAGs marked by alterations in glycosylation=many unclear roles

  1. may process of cleave growth factors and other maternally released factors at trophoblast-uterine interface
    2.May have immunomodulatory functions during pregnancy
  2. Luteotrophic role during pregnancy via increased stimulation of prostaglandin E2 from luteal cells
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13
Q

PAG measurement

A

Measured in serum or plasma using enzyme-linked assays (ELISA) to confirm pregnancy in ruminants

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14
Q

Relaxin in equine

A

-produced in placenta

-Relaxin levels rise quickly reaching peak around mid-pregnancy to parturition

-levels drop after parturition

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15
Q

Relaxin in sow

A

-Maternal serum levels increase dramatically late in pregnancy prior to parturition

**produced in CL. Stored in granules within ovarian CL and released upon luteolysis as parturition nears

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16
Q

Relaxin function in equine and pigs

A
  1. Causes softening or relaxation of pelvic ligaments (pubic symphysis) for aiding fetal expulsion Eg. mare, women
  2. promotes growth and relaxation of uterine muscle during pregnancy
  3. promotes cervical relaxation for parturition
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17
Q

Relaxin in dog

A

-Detected in peripheral circulation by 20-30 days and max levels 5-7 weeks

-undetectable in non-pregnant animal

-maternal blood levels of relaxin is the basis of pregnancy tests in dogs

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18
Q

Relaxin in cats

A

-Appears in blood ~3rd week of pregnancy. Increases and then declines just before parturition

-can also be used for pregnancy diagnosis

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19
Q

Relaxin function in dog and cats

A

To inhibit uterine activity and relax pelvic ligaments

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20
Q

Glucocorticoids

A

A class of steroid hormones produced by adrenal glands (mostly adrenal cortex)

**primarily cortisol in horses, ruminants, pigs, dogs, cats

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21
Q

Glucocorticoid production

A

-Produced on demand, diffuses out of the cells and into the blood to be transported by Corticosteroid binding globulin (CBG) carrier

-When unbound from CBG, cortisol can diffuse into target cells and bind to glucocorticoid receptors to regulate gene expression, transcription, translation

22
Q

Cortisol in ruminants

A

Total maternal cortisol does not change over majority of gestation but spikes at parturition

23
Q

Cortisol in horses

A

Total maternal cortisol fluctuates but increases just before parturition

24
Q

Cortisol in pigs

A

Little change over gestation/birth

25
Q

Fetal cortisol in ruminants and pigs

A

-Fetal adrenals produce almost all of their own cortisol by late pregnancy

**may be reason why maternal levels in these animals don’t change much…fetus is self sufficient

26
Q

Fetal cortisol in horse

A

Fetal adrenals mature a little later than in ruminants, so maternal levels may supplement fetal production

27
Q

Function of cortisol

A
  1. Mediating maternal energy demands
    -freeing up plasma glucose for fetal benefit
    -anti-insulin effect
  2. Triggering maturation of fetal organs (eg. lungs)
  3. initiate parturition
28
Q

Fetal membranes

A

Chorion, amnion, yolk sac, allantois

29
Q

Yolk sac

A

**First to form

-Egg laying vertebrates (birds, reptiles)= mediates nutrition

-Higher mammals= no yolk. But used as first hematopoietic organ (blood cell formation) in mammals and source of primordial germ cells

30
Q

Membrane arrangement

A

Ruminants and pigs: anchor shape

Horses and carnivores: tube shape

31
Q

Chorion

A

-derived from trophectoderm, near embryonic disc, somatic mesoderm

-outermost extra-embryonic membrane which functions in gas exchange, respiration as component of placenta

32
Q

Amnion

A

-most evolutionarily significant membrane to form

-it surrounds the embryo proper and provides an aquatic micro-environment which permits embryogenesis in water analogous to evolutionary ancestors

33
Q

Allantois

A

Acts as a storage bin and mediates gas exchange

**mammals: the size of allantois depends on how well the nitrogenous wastes are removed by chorionic placenta, but it can fill entire extra-embyronic coelom

34
Q

What happens to fetal fluids during gestation?

A

Generally increase

35
Q

Fetal fluids in ruminants and mare

A

-Allantoic fluid increases in first third and then particularly in last third of pregnancy

-amniotic fluid increases particularly in the second third of pregnancy

36
Q

Fetal fluids in sow

A

-Allantoic fluid volume rises quickly by 30 days, reaches max volume by 60 days the declines to term

-Amniotic fluid gradually increases to max 60 days then declines toward term

37
Q

What contributes to the amniotic fluid?

A
  1. Water and solute from maternal plasma- enters fetus from placenta via umbilical cord and then to amniotic fluid
  2. Secretions fro developing resp tract. These fluids can also cross from amnion cavity to fetus via non-keratinized skin

3.Fetal urine- occurs when kidneys are functional and urethra patent

  1. Fetal swallowing adds to fluid movement into lung and GI tract
38
Q

Amniotic fluid molecule composition

A

-carbohydrates, proteins, lipids, enzymes, hormones, growth factors, electrolytes, amino acids, water

39
Q

Roles of amniotic fluid

A

-preventing desiccation
-act as shock absorbed
-nutrition
-innate immunity
-development
-aid parturition

40
Q

What makes up fluid of Allantois?

A
  1. Secretions fo allantois membrane
  2. Urine when kidney functional and urethra patent
  3. Rapid water transfer
  4. Reservoir for nutrients
41
Q

Allantois composition

A

-hormones, fructose, glucose, electrolytes, amino acids (arginine, glutamine)

42
Q

Role of allantois fluid

A

-shock absorber
-nutrition (placenta can metabolize stored nutrients for benefit of placental and conceptus growth

43
Q

Polytocous species

A

-cats, dogs, pigs

-distribution of conceptuses is along the length of the uterine horns, sometimes with nearest one to uterine body extending into both horns

44
Q

Monotocous species

A

-horses, ruminants

45
Q

Ruminants as monotocous species

A

-fetus with amnion and large part of chorioallantois stays in uterine horn adjacent to ovary with CL
-small portion of chorioallantois can push to other horn

46
Q

Mares as monotocous species

A

Majority of chorioallantois and amnion in gravid horn with continuation into uterine body

  • small narrow portion of chorionallantois pushes into nongravid horn
47
Q

Anomalies related to fetal fluids

A
  1. hydrallantois

2.hydramnion

48
Q

Hydrallantois

A

-present 6-9 mths gestation with up to 40x excess fluids

-clinically presents as right abdominal wall distention
*poor prognosis

49
Q

Hydramnion

A

In cows 8-10x normal fluid level in association with malformation of digestive system
*rare in sheep, pigs, dogs, cats. not reported in horses

*usually okay prognosis

50
Q

Why pregnancy diagnosis?

A

-important to detect pregnancy early enough so that steps can be taken to get animal pregnant if needed OR just detect pregnancy

-usually based on idea that failure to return to oestrus=pregnancy occurs
**dog is exception as it is polycyclic

51
Q

Pregnancy diagnosis methods

A

-palpation
-hormone measurement (eg. PAGs, PSPs, eCG relaxin)
-ultrasonography= most immediate, direct, accurate

52
Q

Ultrasonography

A

-used to detect pregnancy by detecting early increase in allantoic and amniotic fluid volumes.
**end of first month in ewe, cow, mare
**dogs and cats at day 25-35

-use B-mode

Animal Production (17 decks)

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